[clang] Call ActOnCaseExpr even if the 'case' is missing #166326
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@llvm/pr-subscribers-clang Author: Timm Baeder (tbaederr) ChangesThis otherwise happens in ParseCaseExpression. Full diff: https://github.com/llvm/llvm-project/pull/166326.diff 2 Files Affected:
diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 92038985f9163..47da1a5b7cdb0 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -813,8 +813,7 @@ StmtResult Parser::ParseCaseStatement(ParsedStmtContext StmtCtx,
return StmtError();
}
} else {
- LHS = Expr;
- MissingCase = false;
+ LHS = Actions.ActOnCaseExpr(CaseLoc, Expr);
}
// GNU case range extension.
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index 91c4ff1cb520d..7e28ac560ed23 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -2661,3 +2661,9 @@ namespace GH154567 {
constexpr S s{};
static_assert(s.val.i == 0, "");
}
+
+constexpr bool missingCase() {
+ switch (1) {
+ 1u: return false; // expected-error {{expected 'case' keyword before expression}}
+ }
+}
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This otherwise happens in ParseCaseExpression. If we don't call this, we don't perform the usual arithmetic conversions, etc.
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Nov 4, 2025
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| constexpr bool missingCase() { | ||
| switch (1) { | ||
| 1u: return false; // expected-error {{expected 'case' keyword before expression}} |
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I'm a bit confused; we already emit this diagnostic today without your changes: https://godbolt.org/z/4379s9zGf
You mention this is about getting the usual conversions to happen, but those only need to happen for well-formed code, right?
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It's not about the diagnostic, it's about clang crashing in constant evaluation because the type of the case stmt expression is wrong: #165555 (the second example further down).
I don't know if the conversions only need to happen for well-formed code or not. If not, we should instead mark the case stmt as having errors I guess, but just letting it through like that trips up a couple of places
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Ah, I see now that my godbolt link does show the issue with an asserts build, that makes more sense now. Thank you!
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/26827 Here is the relevant piece of the build log for the reference |
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This otherwise happens in ParseCaseExpression.
If we don't call this, we don't perform the usual arithmetic conversions, etc.